1. Field of the Invention
The present invention relates generally to a safety device for preventing injectiles propelled within a pipeline from inadvertently escaping the pipeline. More specifically, the present invention relates to a safety device for use with a coupler which prevents an injectile propelled within a pipeline from inadvertently escaping the pipeline at a coupling point removably attaching two sections of pipe. The present invention automatically engages when two sections of pipe are decoupled, thereby safe-guarding the pipeline operator and surrounding area from injury and/or damage due to injectiles that have been previously injected within or passed through a pipeline from inadvertently escaping the pipeline upon decoupling.
2. Background Art
In many areas of modern industry there is an urgent need for a safety device to prevent pipeline operators and the surrounding area from being injured or damaged, respectively, from injectiles that inadvertently escape the pipeline. This need is especially urgent, for example, where devices known as pigs are injected within and propelled through a pipeline. If a pig inadvertently escapes a pipeline, the previously injected mass is projected from the pipeline at a relatively high velocity and may injure any person or object within the pig's trajectory path.
A multitude of injuries occur every year to pipeline operators who mistakenly separate and/or decouple lengths of pipe without first making the proper adjustments to relieve all pressure or other propelling force acting on the pig and thus allows the pig to be projected from the pipeline. Because the pipeline operator stands in relative proximity to the coupling and/or separation point, it is often the pipeline operator who is severely injured. However, due to the velocity with which a pig may be propelled, upon inadvertent release, a pig could project into the area surrounding the coupling point and injure bystanders or damage other material.
A. Pigs
Generally, pigs are bullet-shaped devices that are passed or propelled through a pipeline for a multitude of uses. Pigs are generally known in the prior art and are often either mechanical or chemical. Mechanical pigs normally have wire brushes or abrasive surfaces to physically abrade the scale interior of the pipe. Chemical or gelled pigs are normally chemically based devices that have the ability to conform to the interior shape of the pipeline. Thus, a tight seal can be formed so that material before the pig can be separated from material behind the pig. The separation process permits manufacturers to quickly change fluids within the pipeline without the fear of mixing or interchanging the chemical components of the fluids.
For example, U.S. Pat. No. 4,345,350 issued Aug. 24, 1982, to Burd titled "Pipeline Cleaning Equipment," incorporated herein by reference, discloses a mechanical pig for removing ferromagnetic debris from the internal surface of pipelines. Mechanical pigs, have a variety of uses in connection with the operation of pipelines used for the transport of fluids such as natural gas or oil. They may be used for inspecting the internal surfaces of the pipeline and, for this purpose, carry a variety of test equipment such as polarizing magnets and magnetic field sensors, ultrasonic probes, contact styli or the like.
Still, another form of mechanical pigs serves to clean the pipeline and for this purpose carry brushes and scrapers to remove or loosen scale or other debris from the pipeline surfaces they pass through.
Alternatively, U.S. Pat. No. 4,543,131, issued Sep. 24, 1985, to Purinton Jr., titled "Aqueous Crosslinked Gel Pigs For Cleaning Pipelines," incorporated herein by reference, discloses a chemical or gelled pig containing an aqueous, crosslinked gelled galactomannan gum, or derivative thereof. Such a pig is also used primarily for cleaning the interior of pipelines. Gelled or chemical pigs remove the surface deposits by dissolution and/or by picking up loose debris as they pass through the pipeline. Such pigs can be either passed through the pipeline alone or may be used in pig trains containing one or more chemical pig segments in the train. Other gelled chemical pigs contain bactericides to remove bacteria-containing scale from pipelines.
An advantage of chemical or gelled pigs is that such devices are able to create a tight chemical seal in the pipeline, allowing one to clean the pipelines which are filled with liquid without first evacuating the lines. Passing the gelled pigs with the tight chemical seal, then, displaces the liquid contents of the pipeline ahead of the pig or the pig train, without contamination of materials behind the leading chemical or gelled pig.
In order for pigs to function properly they must be passed through or injected within a pipeline. Some means or force is utilized to propel the pig from one end of a pipeline to the other. Generally, this involves placing greater fluid or air pressure behind the pig than in front of it. After cleaning and/or separation has occurred, procedures are devised to limit the pig's propulsion force so that the pig can be removed from the pipeline safely. However, human error may cause a mistake in the necessary order of the procedures followed or in the manner the propulsion is decreased. Thus, when a pipeline operator attempts to remove the pig from the pipeline the pig may be inadvertently propelled from the pipeline and ultimately injure the pipeline operator or damage other material in the surrounding area.
B. Pipe Union Assemblies
In many areas of modern industry, pigs are removed from the pipeline at a coupling point, i.e., the point at which two pipes are joined by a pipe union assembly. An example of a pipe union assembly is disclosed in Canadian Patent No. 1,303,094 issued Jun. 9, 1992, to Chapmen, et al., titled "Pipe Union Assembly," incorporated herein by reference.
The pipe union assembly disclosed in Canadian Patent No. 1,303,094 relates generally to fitting and couplers for use with pipes and hoses. More particularly the invention disclosed in such patent relates to pipe union assemblies which allow two pipes to be selectively joined together in, and released from, a sealant engagement such that the sealant engagement is maintained under extreme pressure and/or temperature conditions.
Such invention satisfies the urgent need in modern industry for devices which allow two pipes to be repeatedly joined together while allowing for easy separation of the pipes. This need is especially urgent where the substances carried by the pipes are under extreme pressure and/or temperature conditions. The chemical, cryogenic, petroleum and food processing fields are just some examples of the industries having such needs.
The various coupling devices found in the prior art may be called connectors, fittings, unions, couplings, joints, or some other name, but they all serve the same function of joining two pipes.
The pipe union assembly disclosed in Canadian Patent No. 1,303,094 generally comprises at least one hollow-fitting member which may be attached at a first end to a pipe, and a sealing member which may (in at least one embodiment) be attached at a first end to another pipe. Each fitting member is provided with a tapered ridge running parametrically around the end of the fitting member so as to extend axially therefrom. The sealing member is provided with at least one parametric, tapered channel configured in a shape which compliments the shape of the tapered ridge. To provide a sealing engagement between a fitting member and the sealing member, the fitting member tapered ridge is inserted into the sealing member tapered channel.
The planar contact between the sides of the tapered ridge and the walls of the ridge and sealing member channel form a fluid-tight seal. The taper, or angle, of both the fitting member ridge sides and the sealing member channel walls are chosen so as to form the most secure seal possible.
Canadian Patent No. 1,303,094 provides for multiple embodiments of its claimed invention. For example, Canadian Patent No. 1,303,094 discloses one preferred embodiment providing for a restricting means to ensure that the union may be disassembled safely even when residual pressure remains in the system. Such a pipe union assembly is often used in the same industries employing pigs for cleaning and/or separating fluids within a pipeline.
In one embodiment of the invention disclosed in Canadian Patent No. 1,303,094 the union may be disassembled safely, even though residual pressure remains in the system. However, if a pipeline operator disassembles the pipe union assembly with a pressurized pig within the pipeline and fails to previously release the residual pressure in the system, the pipeline operator could be severely injured as the disassembling of the pipe union assembly lowers the pressure at the assembly or coupling point, thereby allowing the pig to inadvertently escape from the pipeline at an injurious momentum.
C. Pig Traps
In an effort to overcome some of the above-mentioned difficulties, pig trap devices have been suggested for use at the end of a pipeline. Generally, such traps are used to insert pigs into or withdraw pigs from a pipeline. Typically, these traps are closed at one end by a solid door or cap to prevent communication between the interior of the pipeline and the atmosphere. When a pig is to be inserted, the door is opened, the pig is inserted and the door is closed for launching the pig into the pipeline. To withdraw the pig from the pipeline, the pig runs into a pipe of the trap, the door is opened and the pig is removed. However, the solid nature of the door or cap precludes an operator from viewing the contents of the pig trap before opening the door.
Pig traps usually include a collar adapted to be attached to the end of a pipe, a door for opening and closing the end of the pipe, means for clamping the door to the collar and sealing means for preventing communication between the interior of the pipe and the atmosphere when the door is clamped to the collar. Each of the different mechanical components comprising a pig trap increases the cost to make pig traps.
Much of the increased need for additional mechanical components of a pig trap lies in the need for the pig trap to remain sealed. Thus, means must be incorporated to seal the collar to the pipe and the door to the collar. Further, certain pig trap devices disclose a testing valve for indicating to the pipeline operator the presence of pressure and fluid in the pipe. However, as previously stated, because the operator is unable to view the interior of the pig trap, there is no possible way to ascertain whether the testing valve is properly reading the pressure inside the pig trap. An operator error in reading the test valve or a mechanical error in the test valve itself could prove fatal to the pipeline operator or any other individual within the surrounding area.
Thus, use of pig traps have several disadvantages. First, pig traps are limited to being clamped at one end of a pipeline.
Second, pig traps cannot be placed at various points along a pipeline, increasing the flexibility for adjusting, moving or changing the length of a pipeline.
Third, pig traps often restrict a pipeline operator's view when trying to determine the presence of a pig that has been released into the system.
Fourth, in order to extend the pipeline, a pig trap will need to be removed from the end of a pipeline prior to attaching the extension.
Fifth, the type of pig trap utilizing a testing valve for indicating the presence of pressurized fluids in the pig trap adds an additional component that is subject to error. For example, a pipeline operator may assume based on a testing valve reading that no pressurized fluids are present in the pipeline. However, the testing valve may be broken and upon opening the trap door pressurized fluids could escape and severely injure the pipeline operator or damage the surrounding area. Additionally, the pipeline operator could simply misread the testing valve, ultimately producing the same injurious effect.
Sixth, pig trap devices typically include multiple mechanical features such as a door, a collar, latches and sealing means, all of which increase the manufacturing cost and ultimate selling price of any pig trap incorporating them.
Seventh, pig traps are sealed devices and retain oil or other fluids expelled from the pipeline.
Thus, requiring further steps to remove trapped fluids.
In view of the foregoing, it would be an advancement in the art to provide a safety device which is not limited to being clamped at one end of a pipeline.
Yet another advancement would be to provide a safety device that can be placed at various points along a pipeline to increase the flexibility of adjusting, moving and/or changing lengths of a pipeline.
Yet another advancement would be to provide a safety device that does not restrict a pipeline operator's view when trying to determine the presence of an injectile that has been released into a pipeline system.
Yet another advancement would be to provide a safety device that does not require removal from the pipeline prior to extending the length thereof.
Yet another advancement would be to provide a safety device that does not necessitate a testing valve that is potentially subject to mechanical or human error to indicate the presence of pressurized fluids in the pipeline.
Yet another advancement would be to provide a safety device which has relatively few working parts and therefore inexpensive to manufacture; resulting in a reduction of the selling price to the ultimate user.
Yet another advancement would be to provide a safety device which channels or deflects oil or other fluids away from the pipeline operator.